MXPA04001838A - Heat and oil resistant polymer blends of polyamides and hydrogenated carboxylated nitrile rubber. - Google Patents

Abstract

A conjugate is formed by blending a polyamide with a hydrogenated carboxylated nitrile rubber at elevated temperature. The conjugate is readily formable by moulding or extrusion, and it displays excellent heat, oil-resistant and barrier properties that render it suitable for use, for example, in many automotive under-the-hood applications.

Description

POLYMERIC MIXES RESISTANT TO HEAT AND OILS FIELD OF THE INVENTION The present invention relates to mixtures of thermoplastic elastomers. A conjugate is formed by mixing a polyamide with a hydrogenated carboxylated nitrile rubber at elevated temperature. The conjugate is easily formed by molding or extrusion and exhibits excellent heat and oil resistant properties and barrier properties which make it suitable for use, for example, in many under hood applications in automobiles. BACKGROUND OF THE INVENTION Thermoplastic elastomers find many applications, for example in coatings, adhesives and molded and extruded parts. The latter are valued for their hardness and resistance to impact and find application in auto parts, mechanical parts, electrical parts and other uses. However, improvements are constantly being sought in the properties and polymer materials are often mixed or combined for this purpose. The present invention is directed, in particular, to heat-resistant materials and oils with good barrier properties and processes for their manufacture. EP-A1-0,364,859 relates to vulcanizable rubber compositions consisting of a polyamide, a partially hydrogenated nitrile rubber and vulcanizers in nitrile rubber. Partially hydrogenated nitrile rubber, mixed with a vulcanizing agent, was added gradually to fused polyamide with mixture. It is said that it is preferred to use a polyamide having a low melting point, such as nylon 12. In a preferred embodiment, the composition includes maleic anhydride or succinic anhydride. The report says that it is believed that the anhydride additive improves mixing between the nylon and the rubber compound. Better results are obtained in an example in which maleic anhydride is used, but the properties of the product obtained are not particularly good and are not suitable for commercial use. US 4,508,867 relates to vulcanizable rubber compositions consisting of a crystalline polyamide, a synthetic rubbery polymer composed of acrylonitrile or methacrylonitrile, an alpha, beta-unsaturated carboxylic acid and a butadiene, an additive selected from lithium halides, magnesium , calcium and zinc, an additive selected from oxides and hydroxides of magnesium, calcium, barium and zinc and calcium and zinc peroxides, and which also contain active sulfur vulcanization agents. Nylon 11 is the only polyamide whose use is exemplified. The descriptive portion of the memory suggests that the mixture of the polyamide and the synthetic rubbery polymer should take place at a temperature of about 50 ° C to about 125 ° C. In Examples 1 and 2, the mixture of nylon 11 and carboxylated nitrile rubber and other ingredients took place at 50 ° C. In Example 3, the mixing took place at a temperature of 190 to 199 ° C and Example 4 does not specify the mixing temperature. It is believed that the compositions of US 4,508,867 do not exhibit adequate heat resistance properties. SUMMARY OF THE INVENTION In one aspect, the invention provides a process of mixing a polyamide with a hydrogenated carboxylated nitrile rubber at a temperature above 20 degrees C to form a conjugate. In another aspect, the invention provides a conjugate or compound of a polyamide and a hydrogenated carboxylated nitrile rubber. The conjugates exhibit some properties which are increased in comparison with the corresponding properties of the polyamide and some properties which are increased in comparison with the corresponding properties of the hydrogenated carboxylated nitrile rubber. In particular, the conjugates exhibit good heat and oil resistance properties and excellent barrier properties. These properties make the conjugates of the invention useful, for example, to contain volatile fuels, such as gasoline, in fuel hoses, fuel tanks, shields, fuel lines and supply hoses, air chambers for tires and industrial air chambers and the like. Another advantage of the conjugates of the invention is that they are recyclable. Any excess or scrap of conjugated material can be melted to remold or re-extrude, for example, without significant deterioration of properties. In this important feature, it differs from most elastomers, which are not recyclable. Moreover, the conjugates of the invention have a lower specific gravity than 100% of the hydrogenated carboxylated nitrile rubber. Therefore, less conjugate by weight is needed to produce a particular part, resulting in a saving in material cost. DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyamides especially useful in the present invention are homopolymers and copolymers having repeated amide linkages along a polymer chain. The polyamides are preferably of high molecular weight and are crystalline or vitreous polymers. Examples include polycaprolactam (nylon 6), polylaurolactam (nylon 12), po-lihexamethylene adipamide (nylon 6,6), polyhexamethylene azide amide (nylon 6,9), polyhexamethylene-nosebacamide (nylon 6,10), po-lihexamethylene isophthalamide (nylon 6, IP ), polyaminoundecaneic acid (nylon 11), polytetramethyleneadipamide (nylon 4,6) and copolymers of caprolactam, hexamethylenediamine and adipic acid (nylon 6,66), and also aramides, such as poliparafe-nileneterephthalamide. Most polyamides have softening points and melting points in the range of 160 ° to 250 ° C. Hydrogenated carboxylated nitrile rubbers (HXNBR) and processes for their preparation are not known in the art and are the subject of our copending Canadian Patent Application 2,304,501, the description of which is incorporated by reference by the Jurisdictions that allow this feature. Said rubbers are formed by copolymerization of at least one diene monomer, preferably a conjugated diene, at least one nitrile monomer, at least one unsaturated acid monomer and optionally other copolymerizable monomers, to form a copolymer with a random or statistical distribution of repeating units derived from diene, nitrile, acid and possibly other comonomers, followed by hydrogenation. When the diene, preferably conjugated, polymerizes, the product contains some carbon-carbon double bonds. In the past, attempts to hydrogenate these carbon-carbon double bonds also led to the reduction of the nitrile and carboxyl groups, which is undesirable. The invention of CA Application 2,304,501 allows the hydrogenation of the carbon-carbon double bonds of the carboxylated nitrile rubber without concomitant reduction of nitrile and carboxyl groups, giving new and valuable polymers. These can now be commercially purchased from Bayer under the trademark Hierban T. Many dienes, preferably conjugates, can be used in the hydrogenated carboxylated nitrile rubber. Mention is made of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and piperylene, of which 1,3-butadiene is preferred. The nitrile monomer is usually acrylonitrile, methacrylonitrile or alpha-chloroacrylonitrile, of which acrylonitrile is preferred. The unsaturated acid is preferably alpha, beta-unsaturated and may be, for example, acrylic, methacrylic, ethacrylic, crotonic, maleic (possibly in its anhydride form), fumaric or itaconic acid, of which Acrylic acid and methacrylic. The conjugated diene normally constitutes 50 to 85% of the polymer, the nitrile usually constitutes 15 to 50% of the polymer and the acid of 0.1 to 10%, preferably 0, 5 to 7%, these percentages being by weight. The polymer may also contain an amount, usually not greater than 10% by weight, of another co-limerisable monomer, for example an ester of an unsaturated acid, for example ethyl, propyl or butyl acrylate or methacrylate, or a vinyl compound , for example styrene, alpha-methylstyrene or a corresponding compound bearing an alkyl substituent on the phenyl ring, for example a p-alkylstyrene, such as p-methylstyrene. It is not important that the values of the repetitive units given above have to be adjusted accordingly to obtain a total of 100% by weight. The polymer is preferably a solid having a molecular weight above 60,000, more preferably above 100,000 g / mol. The degree of hydrogenation can be expressed in terms of residual double bonds (DER), which is the number of carbon-carbon double bonds remaining after hydrogenation, expressed as a percentage of the carbon-carbon double bonds before hydrogenation. HXNBR with DER less than 6 are preferred and HXNBR with DER from 0.9 to 5.5 are particularly preferred. The preferred contents in acrylonitrile are 32%, 33%, 34%, 36%, 39% and 43% (all by weight). In a preferred embodiment of the process, the polyamide is melted and the HX BR is then added to the melt, with stirring in an intensive mixer, such as a Banbury, or in a high cut extruder. The mixture preferably occurs in a single step and is preferably carried out without curing agents. The temperature of the mixture can vary between 150DC and 300 ° C, preferably between 170 ° C and 270 ° C and more preferably between 200 and 250 ° C, depending on the degree of the polyamide. The fill factor, ie, the volume of material that is mixed, expressed as a percentage of the volume of the mixing vessel, is preferably 50% to 95%, preferably 65% to 80%, more preferably 55 to 75% , resulting in higher filling factors in mixtures with better physical properties. The mixer is preferably used at its maximum RPM (95 rpm) or near maximum to ensure good dispersion of the elastomer in the polyamide matrix. Nylon 6, for example, melts at a relatively high temperature in the range of 225 ° C and melted nylon 6 can be at a temperature in the range of 240 ° C. If kept at this temperature for any period of time, the HXNBR can degrade, so it is preferred to minimize the time at this temperature. An antioxidant may also be included in the mixture, suitably in an amount of up to 1.5 phr, preferably 0.7 phr. The mixture is stirred and, if the torque required to drive the agitator is plotted against time, it is seen that the torque increases with time. This indicates ligation or crosslinking between the polyamide and the hydrogenated carboxylated nitrile rubber. When the torque stops growing, this indicates that the crossover has ceased substantially and also that the mixture is complete. As indicated, an antioxidant can be used in the mixing process. Examples of suitable antioxidants include p-dicumildiphenylamine (Naugard® 445), Vulkanox® DDA (a diphenylamine derivative), Vulkanox® Z B2 (zinc salt of methylmercaptobenzimidazole), Vulkanox® HS (1,2-dihydro-2, 2, Polymerized 4-trimethyl-olineoline) and Irganox® 1035 (thiodiethi-wood or bis (3, 5-di-tert-butyl-4-bis (3,5-di-tert-butyl-4-hydroxy) hydroquinone -hydroxyphenyl) thioethylene propionate, supplied by Ciba-Geigy) Vulkanox is a trademark of Bayer AG It is possible to achieve greater crosslinking, so when the torque stops increasing, a crosslinking agent can be added while mixing continues. The crosslinking agent can be a peroxide crosslinking agent, a diamine crosslinking agent, a phenolic or sulfur resin or a sulfur-containing crosslinking agent In many embodiments of the invention, it is desired that the conjugate has good properties at high temperatures and curing with sulfur tends to have a deleterious effect on the properties at high temperatures. It is expected, therefore, to use the sulfur-based curing agents only rarely, but their use is not beyond the scope of the invention. Many peroxidic crosslinking agents are known, including dicumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, 2,2'-bis (tert-butylperoxy) diisopropylbenzene (Vulcup® 40KE), benzoyl peroxide, 2-5. dimethyl-2, 5-di (tert-butylperoxy) hexy-3, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5, bis (tert-butylperoxy) -2,5-dimethylhexane and the like . The high temperature of the polyamide melt, however, influences the selection. The most suitable curing agents are easily accessible by means of a few preliminary experiments. A preferred peroxide curing agent is marketed under the trademark Vulcup® 40KE. The peroxide-based curing agent is suitably used in an amount of 0.2 to 7 parts per hundred parts of rubber (phr), preferably 1 to 3 phr. Too much peroxide can lead to an undesirably violent reaction. The diamine-based curing agents that can be used include aliphatic diamines, for example alpha- and omega-alkylenediamines, such as 1,6-hexamethylenediamine, and cycloaliphatic diamines, such as 1,4-cyclohexanediamine. A convenient source of 1,6-hexamethylenediamine is the hexamethylenediamine carbamate, available under the trademark DIAK 1. The diamine-based crosslinking agent is suitably used in an amount of 0.2 to 20 phr, preferably 1 to 10 phr. . Phenolic resins, such as the bromoethylated formaldehyde alkylphenol resin, known as SP 1055, or the alkylphenol formaldehyde resin (SP 1045), in the presence of a halide-based activating agent, such as stannic chloride, Lewis acid or Neoprene W, will also give place to an effective cross-linking. These are supplied by Schenectady International and can be used at a level of 1 to 10, preferably 5 to 7 phr. You can also use vulcanizing coagents. The triallyl isocyanurate (TAIC), marketed under the registered trademark DIAK 7 of DuPont, or the N, N'-m-phenylene diimaleimide, known as HVA-2 (DuPont Dow), the triallyl cyanurate (TAC) or the liquid polybutadiene, known as Ricon D 153 (supplied by Ricon Resins). The amounts may be equivalent to those of the peroxide curing agent or less, preferably the same. The crosslinking density can also be increased by the addition of an activator, such as zinc peroxide (50% on an inert carrier), using Struktol ZP 1014 in combination with the peroxide. The amounts can be between 0.2 and 7 phr, preferably between 1 and 3 phr. The ratio of polyamide to hydrogenated car-boxylated nitrile rubber can vary widely, preferably from 90 parts to 10 parts by weight and 10 parts to 90 parts by weight. The properties of the conjugate vary depending on the ratio of polyamide to elastomer. A conjugate of 30 parts of polyamide and 70 parts of elastomer was flexible and suitable for use in flexible hoses for use, for example, as fuel lines. A conjugate 50:50 was hard and a conjugate 70:30 was like a plastic and acceptable for rigid fuel lines, but not for flexible conduits. The reason can, of course, be varied to optimize particular properties and tests of conjugates of different proportions can be performed routinely by those skilled in the art. It is possible to include processing oils and prolongers or plasticizers in the conjugate. Suitable plasticizers include those known for use with nitrile polymers, such as phthalate compounds, phosphate compounds, adipate compounds, the al-quilcarbitolformal compounds, the coumarona-indene resins and the like. An example is the plasticizer marketed under the trademark Plasthall 810 or Plasthall TOTM (trioctyl trimellitate) or TP-95 (di (butoxyethoxyethyl) adipate, supplied by Morton International). The plasticizer should be a stable material at high temperature and exuding from the conjugate. If plasticizer is to be used, it is preferred to melt the polyamide, add a first portion of the hydrogenated carboxylated nitrile rubber, say about half, then add the plasticizer, mix and then add the rest of the HXNBR and continue mixing. The amount of plasti fi er used will depend on the proposed end use of the conjugate, but may be between 1 and 40 phr, preferably between 5 and 20 phr. It is also possible to use a mixture of polya-midas. It is also possible to use a mixture of HXNBR or a mixture of HXNBR and another elastomer, for example a carboxylated nitrile rubber (XNBR), a hydrogenated nitrile rubber (HNBR) or a nitrile rubber (NBR), an acetate rubber vinyl (EVM) or an ethylene / acrylate rubber (AEM). Commercially suitable XNBRs of Bayer under the trademark Krynac can be commercially purchased, commercially available HNBRs from Bayer under the trademark Therban and suitable HBRs can be purchased from Bayer under the trademark Perbunan. The EVM can be commercially purchased from Bayer under the trademark Levapren. Vamac® D, an ethylene acrylic elastomer, is marketed by DuPont. If the HXNBR is used in admixture with another elastomer, it is preferred that the HXNBR constitutes at least 25%, preferably at least 50%, of the HXNBR-elastomer mixture. It is possible to incorporate other known additives or mixing agents into the conjugate. These are preferably added after mixing the polyamide and the HXNBR. The additives include reinforcing fillers, for example carbon black, white fillers, calcium carbonate, clay, nanoclay (such as Cloisite 15A, supplied by Southern Clay Products), silica or talc, calcium carbonate, antioxidants, antiozon agents , processing oils, ultraviolet absorbers, thermal stabilizers, coagents and the like. The conjugate of the invention hardens, of course, to form a solid upon cooling. The conjugate can be melted and solidified again without any significant deterioration or deleterious effect on its properties. In this regard, it differs from elastomers such as pure HXNBR, XNBR and HNBR and the like; after crosslinking, they can not be melted and resolidified. This property of the conjugate of the invention is important. It makes it possible to produce the conjugate of the invention in the form of pellets, the pellets of which can be remelted to form final products by, for example, molding or extrusion. It is also possible to recycle the conjugate of the invention, which represents a very significant commercial advantage of the invention.

The invention is further illustrated in the following examples. EXAMPLES General procedure A Plasticorder Brabender was equipped with mixing blades with rollers and a bowl of 369 g capacity. The mixer bowl temperature, fill factor, mixing time and roller speed were varied. In a typical mixing process, the polyamide was initially melted (at 20 ° C more than the melting point of the polyamide), followed by addition of the elastomer and, in some cases, fillers and processing oils, and a curing system. The polymer mixture was then passed through a mill at 70 ° C once to produce a flat sheet. A Preco Press was used to compression-mold the test pieces. The compound was added to a preheated mold and placed in the press at 0 psi and 240 ° C for 10 minutes. The mold was then held at 20,000 psi for 20 minutes, after which the molded sample was transferred to a cold press and maintained at 10,000 psi for 5 min. The polyamide used was polyamide 6 Durethan® B31SK, supplied by Bayer AG. B31S is a re-enforced polyamide with low crystallinity. It has the following desirable properties: high strength, stiffness and abrasion resistance, good chemical resistance and stress cracking, Vicat softening point > 200 ° C, melting point ~ 225 ° C, good barrier properties. Additional polyamides used in the invention and supplied by Bayer include Durethan® B 30 S (melting point 225 ° C), Durethan® CI 31 F (mp 190 ° C) and Durethan® C 38 F (mp 210 ° C). C). As HXNBR, a Therban® XT having carboxyl residues was used, based on approximately 5.0% acrylic acid and with an acrylonitrile content of 33%, the remainder being 1,3-butadiene, with a viscosity of Mooney of 77 and a DER of 3.5%. As HNBR, Therban® A3406 and Therban® C3446 were used; Therban® A3406 has an acrylonitrile content of 34% and a% DER not higher than 0.9; Therban® C3446 has an acrylonitrile content of 34% and a DER of 4%. Example 1 (Comparative) 70 parts (phr - per hundred rubber) of HNBR (Therban® A3406 or Therban® C3446) and 30 parts of polyamide 6 (Durethan® B 31SK) were mixed in the presence of 0.7 phr of Antioxidant Naugard® 445, a peroxide-based curing system, namely 5.3 phr of Vulcup 40KE and 1.1 phr of TAIC, and 0.5 phr of antioxidant Irganox 1035 (bis (3,5-di-t) thioethylene hydroxy-biphenyl-4-hydroxy) or thioethylene bis (3- (3, 5-di-t-butyl-4-hydroxy) phenyl) propionate, supplied by Ciba-Geigy). The mixing conditions of the Brabender were the following: filling factor of 55%, speed of the mixing blades 80 rpm, bowl temperature 230 ° C, total mixing time 12 min. The results are given in Table 1.

Table 1. Physical properties at room temperature for mixtures of 70:30 phr of Therban®: Polyamide 6 (Peroxide / Coagent) * ASTM D 412 ** ASTM D 412 *** ASTM D 412-98 **** &STM D-2240 Example 2 HXNBR (Therban® XT, 70 parts) and polyamide 6 (Durethan® B31SK, 30) were mixed parts), without curing agents. The polyamide was melted and then the HXNBR and 0.7 phr of an antioxidant (Naugard® 445) were added. It was observed that the torque of the mixture increased during a period of about three minutes and then reached an equilibrium level, at which time the mixture was stopped. The results are given in Table 2.

Table 2. Physical properties at room temperature for mixtures of 70:30 phr of Hierban® XT: Polyamide 6 without curing agents; the mixing conditions were variable The product of these cycles shows a tensile strength greater than 7 MPa, a final elongation greater than 100% and a tensile strain of less than 50%. The best results were achieved in cycle B, where the mixture was made with a high filling factor (70%), fast rpm (95) and high temperature (240 ° C). When cycles similar to cycles A were performed, B and C, but using an H BR instead of the HXNBR, no increase in the torque of the mixture was observed in the absence of a curing system, which suggests that there was no interaction between the HNBR and the polyamide. This contrasts with the situation in which HXNBR and polyamide were mixed. The products of cycles A, B and C were aged by heat in an air oven at 150 ° C for 168 hours or for 504 hours and the properties were measured. For comparative purposes, Therban® A3406 was cured by peroxide-cured heat and its properties were measured. The results are given in Table 3.

Table 3. Physical properties aged by heat for 70:30 phr mixes of Therban® X: Polyamide 6 without curing agents; the aging temperature was 150 ° C Physical properties aged by heat for 100 phr of Therban® cured with peroxide and optimized in terms of thermal resistance; the aging temperature was 150 ° C These results show that the long-term heat aging performance of the products of cycles A, B and C exceeds that of Therban® A3406, with good conservation of physical properties such as tensile strength and high to high elongation. temperature. The temperature of brittleness for the product of cycle B exceeded -72 ° C. On the contrary, the product of the mixture of regular H BR (Therban® A3406) with polyamide in the absence of a curing system was melted when it was tried to age at 150 ° C. The permeability of the product of cycle C was measured and it was found to be 3.5 (was2 / (atm-s)) xl08, which compares favorably with the permeability of 3 of a typical tire lining cured with bromobutyl. The products of cycles A, B and C were all reprocessable. Molded test pieces were cut and re-patched several times without any evidence of gel material. The products had excellent flow properties at molding temperatures, for example 240 ° C. Example 3 In this example, HXNBR (Therban® T, 70 parts) and polyamide 6 (Durethan® B31SK, 30 parts) and 0.7 phr of antioxidant (Naugard® 445) were mixed in the presence of 2.2 to 5.3 peroxide curing agent Vulcup® 40KE (2, 2'-bis (tert-butylperoxy) diisopropylbenzene) and 1.1 6 2.2 phr of triallyl isocyanurate coagent (DIA 7, from DuPont). The mixing conditions were maintained constant at 95 rpm, 240 ° C and a filling factor of 65% (Table 4). The results are given in Table 4. Table 4. Physical properties at room temperature for 70:30 phr mixes of Therban®: Polyamide 6 with peroxide-based curing system Example 4 HXNBR (Therban® XT, 70 parts) and polyamide 6 (Durethan® B31SK, 30 parts) and 0.7 phr of antioxydant (Naugard® 445) were mixed with 0.05 to 0.3 phr of curing agent. Functional bi, namely hexamethylenediamine, DIAK 1. The results are given in Table 5. The cycle is comparative, since an HNBR is used, not an HXNBR.

Table 5. Physical properties at room temperature for mixtures of 70:30 phr of Therban®: Polyamide 6 with DIAK 1 curing system; various mixing conditions * Mixing conditions: a = 240 ° C, 95 rpm, filling factor of 70%; addition of DIAK 1 after a mixing time of 8 min. The total mixing time was 9 minutes. b = 230 ° C, 95 rpm, filling factor of 67%; addition of DIAK 1 after a mixing time of 8 min. The total mixing time was 9 minutes. c = 240 ° C, 95 rpm, filling factor of 70%; addition of DIAK 1 once the torque of the polymer mixture was minimized (approximately 5 minutes in the mixture). The total mixing time was 8 minutes. ND = not determined. Example 5 HXNBR (Therban® XT, 70 parts) and polyamide 6 (Durethan® B31SK, 30 parts) and 0.7 phr of antioxidant (Naugard® 445) were mixed. In the O and P cycles, 2.2 phr of Vulcup® 40KE and 2.2 phr of DIAK® 7 were used, added after 7 minutes of mixing.

An amount of 0.15 phr of Irganox 1035 antioxidant was added at the end of the reaction. The mixing conditions in cycles O, P and Q were: temperature 240 ° C; speed 95 rpm; filling factor 70%; Total mixing time 8 minutes. Compound N contained 0.08 phr of Diak 1 as a curing agent, which was added after 7 minutes. The oil resistance of the conjugates formed in ASTM Oil 1 and I M 903 was then measured. ASTM Oil 1 is a mixture of aromatic compounds. IRM 903 is a mixture of naphthenic and paraffinic compounds. The mixtures were aged by heat at 150 ° C for 168 hours in ASTM Oil 1 and IRM 903 and in Tables 6 and 7 the results are given, respectively. Table 6. Results of heat aging for selected Ther- ban® XT / polyamide 6 mixtures at 150 ° C for 168 hours in ASTM Oil 1.

The mixtures cured using peroxide, O and P, exhibited the best overall performance, that is, conservation of physical properties, and had a minimum change in weight and volume after aging by immersion in oil. The tensile strength of all mixtures increased during aging, while the elongation values varied depending on the curing system. The oil resistance of the mixtures is comparable to that of the HNBR control.

Table 7. Heat aging results for selected Therban® XT / polyamide 6 blends at 150 ° C for 158 hours on IRM 903.

The resistance to oils in IRM 903 of the TPE blends is comparable to that of the reference formulation cured with peroxide Therban® 3406. All blends experienced a reduction in hardness and an increase in weight and volume after the test. Example 6 Polyamide 6 (Durethan® G 38 P, 30 phr) (2 ml) at 240 ° C was first melted, followed by the addition of HXNBR (Therban® T, 70 phr) and 1.5 phr of Naugard ® 445. The curing agents were added after 5 minutes to 2.2 phr of Vulcup® 40 KE peroxide, 2.2 phr of TAIC or HVA 2 co-agent and 2.2 phr of zinc peroxide in compounds R to T. Diak 1 (0.05 phr) was added in R to T after 6 minutes. The total mixing time was 7 minutes. The resin (SP 1055) was added at a level of 7 phr after 7 minutes and the reaction was stopped after 9 minutes.

Table 7. Physical properties at room temperature for 70:30 phr mixes of Therban®: Polyamide 6 with and without zinc peroxide in the presence of peroxide or phenolic resin curing systems Example 7 Polyamide 6 (Durethan® C 38 F, 30 phr) (2 min.) At 240 ° C was first melted, followed by addition of HX BR (Therban® XT, 70 phr) or Therban® XT (35 phr) with Therban® A3406 (35 phr) or Therban® XT (50 phr) with Levapren® 700 HV (20 phr) and 0.7 phr of Naugard® 445. The curing agents were added after 5 minutes to 2.2 phr of each of Vulcup® 40 KE peroxide, TAIC or HVA 2 co-agent and zinc peroxide in the V compounds. to X. Diak 1 (0.05 phr) was added in compounds V to X after 6 minutes. The total mixing time was 7 minutes. Compounds V and X also contain 0.5 phr of Armeen D processing aid.

Table 8. Physical properties at room temperature for 70:30 phr Therban® XT / Therban® or / Levapren® Polyamide 6 cured with peroxide EXAMPLE 8 A mixture was prepared by adding Therban® XT (70 phr), antioxidant Naugaurd 445 (1.5 phr), stearic acid (1 phr) and, as fillers, or Vulkasil Al (10 phr) with silane A 172 DLC (72%) (0.5 phr) or carbon black N660 (10 phr) to a 6 x 12 inch mill at 30 ° C and 55 rpm for 11 minutes. The curing agents were added at 2.2 phr of each of Vulcup® 40 KE peroxide, TAIC or HVA 2 coagent and zinc peroxide and 0.05 phr of Diak 1 in the second stage and crushed for 3 minutes at the same temperature . Polyamide 6 (Durethan® C 38 F, 30 phr) was melted in the Brabender (2 min.) At 240 ° C, followed by addition of the mixture. The reaction was completed after 7 minutes.

Table 9. Physical properties at room temperature for 70:30 phr Therban® XT with Polyamide 6 cured peroxide and with fillers Filler Number Strength Lengthening Compound hardness (%) ** (Shore tion (MPa) * *** Z None 22,43 425 87 AA Filler 19, 92 318 88 white AB Filler 15,59 294 87 black

Claims (16)

1. CLAIMS 1. A process consisting of mixing a polyamide with a hydrogenated carboxylated nitrile rubber at a temperature above 20 degrees C to form a conjugate.
2. 2. A process according to claim 1, wherein the polyamide is polyamide 6.
3. 3. A process according to claim 1 or 2, wherein the hydrogenated carboxylated nitrile rubber is a copolymer of acrylonitrile, butadiene and acrylic acid, having a content in residual carbon-carbon double bonds of 6% or less.
4. 4. A process according to claim 1, 2 or 3, wherein the temperature is 150 to 300 ° C.
5. 5. A process according to any of claims 1 to 4, wherein the mixing is carried out in a mixing medium with a packing factor of 50 to 95%.
6. 6. A process according to any of claims 1 to 5, which consists in melting the polyamide and adding the hydrogenated carboxylated nitrile rubber to the molten polyamide with stirring and in the absence of any curing system.
7. 7. A process according to claim 6, wherein the mixing torque is observed and, when the mixing torque stops increasing, a curing system is added to the mixture.
8. 8. A process according to any of claims 1 to 5, which consists of melting the polyamide and adding the hydrogenated carboxylated nitrile rubber and a curing system to the molten polyamide.
9. 9. A process according to claim 7 or 8, wherein the curing system is selected from the group consisting of a peroxide-based curing system, a diamine-based curing system, a curing system based on phenolic resin or its mixtures
10. 10. A process according to claim 9 in the presence of zinc peroxide.
11. 11. A process according to any of claims 1 to 10, which includes the step of forming the conjugate into pellets suitable for use in molding or extrusion operations.
12. 12. A conjugate of a polyamide and a hydrogenated carboxylated nitrile rubber.
13. 13. A conjugate according to claim 12, which has been formed with the aid of a curing agent.
14. 14. A conjugate according to any of claims 12 to 13m, further comprising hydrogenated nitrile rubber, ethylene and vinyl acetate rubber, ethylene acrylate polymer or mixtures thereof.
15. 15. A conjugate according to any of claims 12 to 14 in the form of pellets.
16. 16. A conjugate according to any of claims 12 to 15 in the form of a molded or extruded part.